title: Postpartum translabial 2D and 3D ultrasound measurements of the anal sphincter complex in primiparous women delivering by vaginal birth versus Cesarean delivery.
abstract: OBJECTIVE
  Consensus on normal translabial ultrasound (TL-US) anal sphincter complex measurements for postpartum women is lacking. We aimed to evaluate normative measurements in 2D and 3D TL-US for the anal sphincter complex (ASC) at 6 months postpartum and compare these measurements in women who had a vaginal birth (VB) and in those who had a Cesarean delivery (CD).
  
  
  METHODS
  A large, prospective cohort of primiparous women underwent 2D and 3D TL-US 6 months after their first delivery. For normative sphincter measurements, we excluded women with third- or fourth-degree lacerations or with sphincter interruption on TL-US. Measurements included the sphincter thickness at the 3, 6, 9, and 12 o'clock positions of the external anal sphincter (EAS) and the internal anal sphincter (IAS) at proximal, mid, and distal levels. We also measured the mean coronal diameter of the pubovisceralis muscle (PVM).
  
  
  RESULTS
  696 women consented to participate, and 433 women presented for ultrasound imaging 6 months later. Women who sustained a third- or fourth-degree laceration had significantly thicker EAS measurements at 12 o'clock. Sphincter asymmetry was common (69 %), but was not related to mode of delivery. Only IAS measurements at the proximal and distal 12 o'clock position were significantly thicker for CD patients. There were no significant differences in the EAS or PVM measurements between VB and CD women.
  
  
  CONCLUSIONS
  There appear to be few differences in normative sphincter ultrasound measurements between primiparous patients who had VB or CD.
authors.affiliation: Department of Obstetrics and Gynecology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA, meriwet2@salud.unm.edu.
authors.forename: Kate V
authors.initials: KV
authors.lastname: Meriwether
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Hall
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Leeman
authors.forename: Laura
authors.initials: L
authors.lastname: Migliaccio
authors.forename: Clifford
authors.initials: C
authors.lastname: Qualls
authors.forename: Rebecca G
authors.initials: RG
authors.lastname: Rogers
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000293:injuries; D002585:Cesarean Section; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D022125:Lacerations / Q000000981:diagnostic imaging; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D007744:Obstetric Labor Complications / Q000000981:diagnostic imaging; D010298:Parity; D036801:Parturition; D010502:Perineum / Q000293:injuries; D049590:Postpartum Period; D011247:Pregnancy; D011446:Prospective Studies; D012016:Reference Values; D014463:Ultrasonography / Q000379:methods; D055815:Young Adult